Piet O. Schmidt
Precision Measurements using Quantum Logic Spectroscopy
Quantum computing based on trapped ions has flourished over the past decade, demonstrating exquisite control of the internal and external degrees of freedom of the atoms. Only now, first applications of the developed techniques start to emerge. One of these applications is the so-called quantum logic spectroscopy in which a logic ion is used for laser cooling, internal state preparation, and detection of the internal state of a spectroscopy ion. This opens the door to perform precision spectroscopy on atomic and molecular ions with a complex level structure. I will present quantum logic spectroscopy schemes for metal ions using direct frequency comb spectroscopy. For this, an optical frequency comb is used to excite the spectroscopy transitions, while cooling and detection is performed using quantum logic via a simultaneously trapped logic ion. The investigated atoms are relevant for the search of a possible temporal variation of the fine-structure constant on cosmological timescales using quasar absorption spectra. Furthermore, the technique might allow cooling of molecular ions to their internal ground state.
